The Universal Self is the eighth and final layer of the soul's architecture — but unlike the other seven layers, it is not really a layer at all. It is the ground from which all layers arise, the awareness in which all experience occurs, the silence that underlies all sound. The map metaphor breaks down here: the Universal Self is not a region on the map but the paper on which the map is drawn.
In Advaita Vedanta — the non-dual tradition of Shankara, Ramana Maharshi and Nisargadatta Maharaj — the central teaching is Tat tvam asi: "That thou art." The Atman (the individual self) is identical with Brahman (the universal reality). The appearance of separation — of being a particular, bounded self in a world of other separate things — is maya, the cosmic illusion that is the ground-level condition of individual consciousness. The spiritual path, in this framework, is not the development of the individual self but the recognition that the individual self was never truly separate — that what you fundamentally are is the universal awareness that was temporarily pretending to be a particular person.
This recognition is not the elimination of the individual — it is the correct understanding of its nature. After the recognition "I am not a person who has awareness; I am awareness that appears as a person," the person continues to exist, to function, to have relationships and experiences. But the relationship to the person changes entirely: it is seen as an appearance in awareness rather than as what awareness fundamentally is. The wave has recognised that it is the ocean making a wave-shape — and it can continue to be a wave, with all the specific character and individuality that entails, without the terrifying belief that it is only a wave and will be destroyed when it breaks.
The great paradox of the Universal Self is that it cannot be found by seeking it — because the seeker is an expression of what is being sought. Every effort to grasp the Universal Self is made by the separate self, which is the very thing that needs to be seen through. The recognition tends to arise not through effort but through the exhaustion of effort — in the gap between thoughts, in profound stillness, in the moment when the seeking temporarily falls away and what was always already present becomes briefly obvious.